Electronic mail (e-mail) is used with increasing frequency as the Internet becomes more widespread. Conventionally, in transmission and reception of e-mail, an e-mail message is sent out with time information that is attached in a sender's PC (Personal Computer). Then, a receiver's PC receives the e-mail via the Internet and displays the e-mail message on a PC screen. Here, generally, the time information attached to the e-mail in the sender's PC is displayed at the receiver's PC as the sending time for the e-mail message.
As another example, one can register to win a prize or fill out a questionnaire on a website that is made public on the Internet. In the case of registration to win a prize, a registrant enters predetermined data such as his name and address in a registration form presented by a server of the prize provider and transmits the data on the registrant's PC. When the transmitted data reaches the server of the prize provider via the Internet, the server checks the registration (for example, whether it meets predetermined registration conditions or not) and then accepts the registration.
In this case, unlike the case of transmission and reception of e-mail, it is generally agreed that the time when the server accepts the registration is “registration time.” However, this approach is problematic, for the following reasons.
An Internet user's PC has an internal clock. Based on the time information provided by the clock, time information to indicate the sending time is attached to e-mail. However, the internal clock is not necessarily highly accurate. Similarly, a server and mail server of each service provider also have internal clocks, but the clocks are not guaranteed to be accurate. Thus, the accuracy of the time information attached to e-mail in transmission and reception is questionable.
As a result, there is a problem when the sending time is critical, especially in business, when contracts must be accurately time stamped. This also applies to registration to win a prize and answering a questionnaire. Particularly, there is inconvenience often when the “registration time” is critical, e.g., when a deadline is set for registrations or when registrations are accepted on a first-come-first-served basis. In this case, a registration may not meet the registration deadline due to the misaligned time setting of the time information maintained in the server although the registration was actually received before the deadline.
Further, since the server accepts registrations from registrants after checking the registration data, the data checking process may overload the server when a large number of registrations arrive simultaneously. This may lead to slow processing and ultimately to server overflow. Then, many of the registrations may not meet the deadline because the server regards their “registration time” as the point when it accepted the registrations as mentioned above.
Thus, there is a need for a way of providing accurate time information when exchanging data such as e-mail on a network.